An estimated 1,500 to 2,500 fish in the lake at City Lake Park were killed Oct. 5-6, probably from oxygen depletion caused by a dramatic drop in temperature.
Trevor Tanner, a wildlife biologist with the Texas Parks & Wildlife Department office that serves Rockwall County, said that’s the “likely cause” of the fish die-off.
Tanner said the temperature dropped 30-plus degrees when the cold front arrived in Royse City on Oct. 5. That temperature drop, he said, probably caused the lake to turn over, sending warm water to the top and cool water to the bottom of the lake.
That turnover, he said, likely depleted oxygen in the water, causing the fish to suffocate.
Most of the fish killed were shad, small fish that are about three inches in length.
He said they represented 1,500 to 2,000 of the total killed. Others included 40-50 bass and 15-20 catfish.
The city lake possibly was affected because it probably isn’t very deep, Tanner said.
Tanner said he believes there are still fish in the lake.
“I think there are still some. I don’t think it was a total kill,” Tanner said. “It was a setback for the lake. There are still some fish there, but it will take time to recover. The lake lost some larger, older fish and it will take the remaining fish to grow to that size.”
Tanner said there was no evidence that the fish die-off was caused by an influx of toxins or chemicals.
Janey McPherson, director of planning and community development, said she received a call on Oct. 7 regarding dead fish in the lake. After a brief investigation, she called the Texas Parks & Wildlife Department.